Benefit Obligations (Details 4) (Pension Benefits [Member], USD $) In Thousands, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010
Pension Benefits [Member]
Plans with Projected Benefit Obligation and Accumulated Benefit Obligation in excess of Plan Assets
Projected benefit obligation	$ 1,455,297	$ 1,324,302
Accumulated benefit obligation	1,453,690	1,322,394
Fair value of plan assets	$ 857,259	$ 860,414

If aggregate disclosures are presented, the aggregate pension accumulated benefit obligation for pension plans with accumulated benefit obligations in excess of plan assets as of the measurement date of each statement of financial position presented.

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If aggregate disclosures are presented, the aggregate fair value of plan assets for pension plans with accumulated benefit obligations in excess of plan assets as of the measurement date of each statement of financial position presented.

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- Definition

If aggregate disclosures are presented, the aggregate projected benefit obligation for pension plans with accumulated benefit obligations in excess of plan assets as of the measurement date of each statement of financial position presented.

+ References+ Details